I use mine while waiting for SBR stamp. That way I can build the upper and just run a pistol lower until the stamp is received.
I prefer a real stock for adjustability with clothing or gear, also a real stock has better sling attachment methods. But on the other hand the Sig brace gets the job done rather well just have to sacrifice these two items. As far as comfort and cheek weld it fells like the real deal.
I us to refrain from commenting on shouldering these, but after the letter from the ATF on this matter I am comfortable putting my thoughts on an public format. Even though back then I knew shouldering wasn't illegal I didn't want to attract attention.